EP2509779B1 - Method and press for manufacturing a bead ring for a tire - Google Patents

Description

The invention relates to the manufacture of rods for the realization of vehicle tires.

The tires comprise an annular reinforcing rod in each bead used for fixing the tire to the rim. On heavy trucks, this rod comprises a metal frame of rectangular cross section, coated with rubber to facilitate the shaping of the tire blank during its manufacture. This coating is placed on the frame in its circumferential direction. When the entire length of the armature has been coated, the two circumferential ends of the coating are superimposed to form an extra thickness.

But this geometrical singularity generates vibrations when the vehicle rolls so that we try to eliminate it. For this, we can consider pressing the area of recovery in a press between two jaws. But this pressing causes a creep between the jaws of the gum forming the coating which also generates geometric irregularities, as well as pressing residues.

The document US 1463868 - A discloses a method of manufacturing a bead wire for the production of a tire, the bead wire comprising a coating forming an overlap zone on itself in a circumferential direction of the bead wire, in which process the bead is pressed by means of a pressing device in contact with a whole perimeter of a section of the zone.

An object of the invention is to improve the treatment of the geometrical singularities of the rods comprising a coating.

For this purpose, according to the invention, a method as defined in claim 1 is provided for the manufacture of a bead wire intended for the production of a tire and comprising a coating forming a covering zone on itself in one direction. circumferential rod, method wherein the rod is pressed by means of at least three jaws in contact with a whole perimeter of a section of the zone.

Thus, the creep of the coating material is better controlled, which improves the regularity of the profile of the bead wire along its circumference. This reduces the vibrations felt in the vehicle.

Preferably, the number of jaws is at least four.

It is thus possible to press the bead wire between each of the two pairs of jaws.

Advantageously, the rod is placed on the lower one of the jaws.

Preferably, the bead wire is first pressed by means of two opposite jaws, preferably upper and lower jaws, while two more jaws, preferably lateral jaws, are held together. away from the rod.

Thus, the creep control of the material during the pressing is improved.

Advantageously, after pressing between the two opposite jaws, they are immobilized relative to the rod and the other two jaws of the rod are approached.

Preferably, after pressing between the two opposite jaws, the rod is pressed by means of all the jaws.

Advantageously, during pressing, a mark is made on the rod, making it possible to differentiate two axial faces of the rod from one another.

Thus, during the subsequent placement of the rods within a green tire blank, the operator can easily recognize each of the two axial faces of each rod to orient them properly within the blank.

Advantageously, the rod comprises a frame of polygonal section.

Preferably, the coating comprises a cushioning layer and a covering layer.

According to the invention there is also provided a press as defined in claim 9, for a bead wire intended for producing a tire, the press comprising at least three jaws mounted movable relative to one another and able to form between them a cavity with closed section.

• elle comprend un mors supérieur, un mors inférieur et deux mors latéraux ;
• elle comporte un équipage monté mobile par rapport à l'un des mors, de préférence un mors inférieur, et portant les autres mors ;
• au sein de l'équipage, deux des mors agencés pour presser la tringle entre eux, de préférence des mors latéraux, sont montés mobiles par rapport au troisième ;
• les mors sont montés mobiles à coulissement par rapport à un bâti de la presse, et la cavité a une section présentant un axe de symétrie principal incliné par rapport à des directions de coulissement des mors ;
• chaque mors est revêtu d'au moins une couche antiadhésive ; et
• la presse comprend des moyens de chauffage des mors. Des formes préférentielles de l'invention sont définies dans les revendications dépendantes.

The press according to the invention may also have at least one of the following characteristics:

• it comprises an upper jaw, a lower jaw and two lateral jaws;
• it comprises a crew movably mounted relative to one of the jaws, preferably a lower jaw, and carrying the other jaws;
• in the crew, two jaws arranged to press the rod between them, preferably side jaws, are mounted movable relative to the third;
• the jaws are slidably mounted relative to a frame of the press, and the cavity has a section having a main axis of symmetry inclined with respect to directions of sliding of the jaws;
• each jaw is coated with at least one nonstick layer; and
• the press comprises means for heating the jaws. Preferred forms of the invention are defined in the dependent claims.

• la figure 1 est une vue en coupe transversale montrant la section courante d'une tringle avant la mise en oeuvre du procédé de l'invention ;
• la figure 2 est une vue de la section du revêtement de la tringle de la figure 1 avant mise en place sur l'armature de cette dernière ;
• les figures 3 et 4 sont deux vues en élévation d'une presse selon l'invention respectivement à l'état ouvert et à l'état fermé ;
• les figures 5 et 6 sont des vues de face à plus grande échelle des mors de la presse respectivement en positions fermée et ouverte ;
• la figure 7 est une vue en perspective des mors de la figure 5 ;
• les figures 8 et 9 sont des vues respectivement de dessous et en coupe verticale du mors supérieur de la figure 5 ; et
• la figure 10 montre la forme de la section transversale de la tringle dans sa zone de recouvrement après mise en oeuvre du procédé.

Other features and advantages of the invention will become apparent in the following description of an embodiment given by way of non-limiting example with reference to the accompanying drawings in which:

• the figure 1 is a cross-sectional view showing the current section of a bead wire before carrying out the method of the invention;
• the figure 2 is a view of the section of the coating of the rod of the figure 1 before placement on the frame of the latter;
• the Figures 3 and 4 are two views in elevation of a press according to the invention respectively in the open state and in the closed state;
• the Figures 5 and 6 are front views on a larger scale of the jaws of the press respectively in closed and open positions;
• the figure 7 is a perspective view of the jaws of the figure 5 ;
• the Figures 8 and 9 are views respectively from below and in vertical section of the upper jaw of the figure 5 ; and
• the figure 10 shows the shape of the cross section of the rod in its recovery zone after implementation of the method.

An orthogonal reference mark X, Y, Z is used in the following, in which the X and Y directions are horizontal and perpendicular to each other while the Z direction is vertical.

We will first describe, with reference to Figures 3 to 9 , the press 2 of the present embodiment of the invention. The press is used for the manufacture of rods 4 themselves involved in the production of raw blanks of vehicle tires, for example of the heavy truck type.

The press 2 comprises a fixed frame 6. It is provided with at least three jaws which are in this case four in number. We thus distinguish a lower jaw 8, an upper jaw 10, a left lateral jaw 12 and a right lateral jaw 14.

In this case, the lower jaw 8 is fixed rigidly to the frame 6,

The press comprises a crew 15 mounted to slide relative to the frame in the vertical direction Z. The crew 15 comprises in particular a plate 16 which carries the upper jaw 10 and the two lateral jaws 12 and 14. The upper jaw 10 is rigidly attached to the plate 16. The two lateral jaws 12 and 14 are each movably movable relative to the plate 16 in the Y direction and coaxially to each other. The press comprises a pneumatic guiding unit 11 ensuring the displacement of the plate 16 in the vertical direction relative to the frame, as well as a pneumatic guiding unit 13 ensuring the displacement of each of the lateral jaws with respect to the plate 16.

Each of the jaws is removably mounted relative to the frame so that it can be easily disassembled, reassembled and, if necessary, replaced. The press comprises means for heating each jaw, for example by means of electric cartridges not shown. The press is thus able to keep each of the jaws at a temperature of, for example, between 120 and 150 ° C.

With reference in particular to Figures 5 and 6 , each of the lower jaw 8 and upper 10 has a flat horizontal main face 16, 17 started in a median zone by a shaping face 18, 19. The face 16 of the lower jaw is oriented upwards while the face 17 of the upper jaw is facing the low. Each of the side jaws 12 and 14 has a lower horizontal planar face 20 facing downwards, and an upper horizontal planar face 22 facing upwards. The faces 16 and 20 are facing each other, as well as the faces 17 and 22. The horizontal faces 16 and 20 are arranged to come into mutual surface contact during the operation of the press and so that each face 20 slides relative to the face 16 in the Y direction. The same is true for the faces 17 and 22. The horizontal faces 20 and 22 of the left lateral jaw are each limited to the left by a shoulder 30 forming a stop for edges 32 lower jaw 8 and upper jaw 10 respectively. This abutment therefore marks the end of the race of the left jaw 12 towards the right. The right lateral jaw 14 cooperates similarly with the lower and upper jaw faces to mark the end of the race to the left of the right lateral jaw 14.

The left lateral jaw 12 has a shaping face 24 delimited downwards and upwards by the faces 20 and 22 with which it forms edges. It is the same for the shaping face 26 of the right lateral jaw 14 with respect to the horizontal faces 20 and 22, the shaping faces 18 and 19 extend opposite and at a distance one of the other. It is the same for the shaping faces 24 and 26.

The press is arranged so that, in the closed position, when the four jaws are in the configuration illustrated in FIG. figure 5 in which they are closest to each other, the four shaping faces 18, 24, 19 and 26 form in this order a closed continuous succession which constitutes a cavity 40 open at its two axial ends in the X direction, but closed in a plane of any vertical section parallel to the Y and Z directions. The section in this plane is not circular but has a principal axis of symmetry 42 inclined with respect to each of the directions Y and Z. The section has in particular a rectilinear base 44, two chamfers 46 and 48 extending from the ends of the base 44 and a concave curved arch 50 joining the ends of the chamfers. The shaping face 18 corresponds to the segment 44 and the left chamfer 46. The arch 50 is defined by the faces 24 and 19. The face 26 defines a fraction of the arch and the left chamfer 48.

After machining, each of the jaws is in this case coated with at least one layer of a non-stick coating 62 such as that marketed under the reference FEP Xylan 8840/2618. In the present example, each jaw is coated with a primary layer of this product after having worn the jaw at a temperature of at least 120 ° C. Then after raising its temperature to 400 ° C, a top coat of the same product is applied. The total thickness of the layers is between 20 and 30 microns. The layers extend on the faces 16, 20, 22 and 17 to facilitate their sliding on one another as well as on the shaping faces.

The method according to the invention is here implemented as follows.

It is assumed that an annular bead ring was made as illustrated in FIG. figure 1 , the ring having a main axis 53. The rod comprises a central armature 52 forming the core of the section. This frame is formed of metal strands arranged side by side and stacked, and has a general shape of polygon, for example quadrilateral and in this case rectangle. The armature 4 is provided with a coating 54 comprising in this case an inner cushioning layer 56 in contact with the armature and an outer covering layer 58. In this case, the two layers form a complexed product co -Extruded and include each of the eraser. Before placement on the frame 52, the coating 54 extends flat and has an open section illustrated in FIG. figure 2 . When setting up, this section is wrapped around the section of the frame. This installation is done following the circumference of the armature, that is to say, locally its longitudinal direction. The two longitudinal ends of the coating thus form a mutual overlap zone in the circumferential direction.

For the shaping of this overlap zone, the procedure is as follows.

The press is initially opened as shown in figure 3 that is, the crew 16 is in its highest position relative to the lower jaw 8. In addition, the side jaws 12 and 14 are in their furthest position from each other and from the upper jaw 10 The horizontal faces 22 and 17 are in contact over a fraction of their length. The horizontal faces 16 and 20 are not in contact.

The rod 4 is placed in the press 2 with the overlap area on the lower jaw 8 and the main axis 53 parallel to the Y direction.

The crew is lowered to press the bead overlap area between the upper and lower jaws 10. This zone is pressed between these two jaws by compressing the coating, causing it to flow in the Y direction. towards the side jaws. During the descent, the horizontal faces 16 and 20 come into mutual contact on a fraction of their surface,

Then, while keeping the lower jaws 8 and upper 10 in position, the lateral jaws are approached from one another by sliding them in the direction Y. During this movement, the faces 20 slide on the face 16 by staying in surface contact with them. It is the same for the faces 22 with respect to the faces 17. The side jaws therefore come into contact with the coating they press between them. From this contact, the rod is pressed simultaneously between the four jaws. At the end of the movement of the jaws, the four shaping faces constitute the closed-section cavity 40 in which the overlap zone between the four jaws is pressed and heated, as illustrated in FIGS. figures 4 , 5 and 7 . The gum is therefore forced to spread by creep in this section to take a male form illustrated in the figure 10 corresponding to the female form of the cavity 40. The pressure is maintained for a few seconds in this position so that the rubber takes its place.

The press is then opened. For this, the lateral jaws 12 and 14 are moved away from each other, then the plate 16 which carries the two lateral jaws and the upper jaw 10 is raised. The rod can then be removed.

After pressing, the flat bottom face of the armature 52 is parallel to the underside of the section of the rod defined by the segment 44. The hot pressing also makes it possible to perform a welding of the coating on itself at the of its parts in recovery.

As illustrated in Figures 8 and 9 , one of the jaws, in this case the upper jaw 10 comprises a geometric singularity in the form of a relief or a cavity. In the present case, it is a cavity 60. This singularity has a positioning and / or a shape making it possible to distinguish the two axial faces 64 of the bead wire from one another at the end of the implementation. shape of the overlap area. These faces 64 are perpendicular to the axis 53. In the present case, the cavity 60 has a shape in "V", the axis of symmetry of the "V" being parallel to the direction Y. The cavity 60 extends into the highest part of the shaping face 19. During the implementation of the method, it allows to make, at the top of the section of the overlap zone, a mark 59 in "V" in relief. This mark will allow the operator to place the bead wire in the raw tire blank with a predetermined orientation of its axial faces 64.

The invention is applicable to the manufacture of tires for wheels of light-weight vehicles, heavy vehicles or civil engineering.

Of course, we can bring to the invention many changes without departing from the scope thereof.

We can consider giving the press only three jaws.

We can modify the movements of the jaws, including their direction and their order of movement.

Claims (15)

1. Method for manufacturing a bead wire (4) intended for producing a tyre, characterized in that, with the bead wire comprising a coating (54) that forms a region that overlaps itself in a circumferential direction of the bead wire, the bead wire is pressed using at least three jaws (8, 10, 12, 14) in contact with an entire perimeter of a section of the region.
2. Method according to the preceding claim, in which the number of jaws is at least four.
3. Method according to at least one of the preceding claims, in which the bead wire is pressed first of all by means of two mutually opposed jaws, preferably lower (8) and upper (10) jaws, while two more of the jaws, preferably lateral jaws (12, 14) are held away from the bead wire.
4. Method according to the preceding claim in which, after the pressing between the two opposed jaws (8, 10), these are immobilized with respect to the bead wire and the other two jaws (12, 14) are brought in closer to the bead wire.
5. Method according to at least any one of Claims 3 and 4, in which after pressing between the two opposed jaws (8, 10), the bead wire is pressed using all the jaws.
6. Method according to at least any one of the preceding claims, in which, during pressing, a mark (59) is made on the bead wire so that the two axial faces (64) of the bead wire can be differentiated from one another.
7. Method according to at least any one of the preceding claims, in which the bead wire comprises a reinforcement (52) of polygonal cross section.
8. Method according to at least any one of the preceding claims, in which the coating (54) comprises a padding layer (56) and a cladding layer (58).
9. Press (2) for a bead wire (4) intended for producing a tyre, characterized in that the press comprises at least three jaws (8, 10, 12, 14) mounted with the ability to move relative to one another and able to form between them a closed-section cavity (40).
10. Press according to the preceding claim which comprises an upper jaw (10), a lower jaw (8) and two lateral jaws (12, 14).
11. Press according to at least either one of Claims 9 and 10, which comprises gear (15) mounted with the ability to move with respect to one of the jaws, preferably a lower jaw (8), and which bears the other jaws.
12. Press according to the preceding claim in which, within the gear (15), two of the jaws arranged to press the bead wire between them, preferably lateral jaws (12, 14), are mounted with the ability to move relative to the third one (10).
13. Press according to at least any one of Claims 9 to 12 in which the jaws are mounted with the ability to move in a sliding manner with respect to a frame (6) of the press, and the cavity (40) has a cross section exhibiting a main axis of symmetry (42) that is inclined with respect to directions (Y, Z) in which the jaws slide.
14. Press according to at least any one of Claims 9 to 13 in which each jaw (8, 10, 12, 14) is coated with at least one nonstick layer (62).
15. Press according to at least any one of Claims 9 to 14, which comprises means of heating the jaws (8, 10, 12, 14).

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